so you are having to float her rent a month. 

Which means you need enough cash to float vacancies.

I'd hate to see you work and work and work only to have it so far under water she'll never float ya know?  

If any of the water goes near any of the edges on any floating floor, the water is now under your floor.

Many municipalities didn't start floating, broom-finishing and edging sidewalks in these here parts before the 1990s. 

Float a luxury vinyl plank over that flooring. 

And those in the middle will float along, salary increasing, along with everything else, as a cup of coffee exceeds $10. 

For instance, you can float a small increase for existing leases and if you get pushback can scale back.

ALSO...I would rather put down a layer of subfloor over the existing wood floor and then, sound absorbing dense underlay foam, and then new vinyl or laminate floating floor(faux wood) floors..than mess around with any BS carpet.In case I haven't been clear enough about my opinion....NO CARPET!

You can do this by installing a floating floor in the upper unit or using a 2nd drywall ceiling in the basement isolated with j-clips. 4) Other secondary tactics involve installing material that absorbs sound energy.